Prefabricated spiral staircase

ABSTRACT

The present invention relates to a prefabricated spiral staircase in which the heights between treads can be freely and finely adjusted, thus being conveniently assembled and installed at installation sites having different story heights.

TECHNICAL FIELD

The present invention relates to a prefabricated spiral staircase inwhich the heights between treads can be freely and finely adjusted, thusbeing conveniently assembled and installed at installation sites havingdifferent story heights.

BACKGROUND ART

Staircases are divided into linear staircases and curved staircases.

Linear staircases have linear shapes, and refer to staircases having aladder form.

Curved staircases are basically divided into spiral staircases with acenter pole and double helical staircases without a center pole.

Spiral staircases can be assembled at installation sites in the mannersdescribed in patent documents 1 and 2, unlike double helical staircases.

As shown in FIGS. 1 and 2, the prefabricated spiral staircase 1 ofpatent document 1 includes: a post 2 configured to be placed upright andfastened via anchor bolts 3, and fabricated to have a height suitablefor the height of a corresponding story; spacer-bushes 5 configured tobe inserted over the post 2; treads 4 configured to be inserted over thepost 2 alternately with the spacer-bushes 5; brackets 7 fastened to thetreads 4 in an integrated manner, and configured to include couplingholes 6 adapted to be inserted over the post 2; and handrails 8configured to be inserted into a plurality of coupling holes 9 formed atthe outer ends of the treads 4, and each configured to be inserted intoall the coupling holes 9 formed in vertically adjacent two of the treads4. Of the treads 4, a fastening tread 4 a configured to be installed atthe uppermost end is fixedly installed on the slab 10 of a correspondingstory or the like, and some of the coupling holes 9 configured to enablethe handrails 8 to be coupled thereto are formed in the fastening tread4 a.

By the way, a story height, e.g., the height between a first floor and asecond floor, at an installation site usually and slightly variesdepending on the construction situation of a building or the like. Forsuch a difference, in the case of the prefabricated spiral staircase 1of patent document 1, the spacer-bushes 5 suitable for a story heightmust be prepared or the spacer-bushes 5 must be cut or attached throughwelding or the like at a site on each occasion, thereby makinginstallation inefficient or causing material to be wasted.

Meanwhile, in patent document 1, the fastening treads 4 a are moreweakly supported than the fastening treads 4 a supported by side platesbecause the fastening treads 4 a are held by the handrails 8, i.e.,stringers, composed of U-shaped rods.

Furthermore, the fastening treads 4 a of patent document 1 are installedin such a way that they are inserted over the post 2, and thus thetreads 4 are simply disposed stepwise. Accordingly, the treads 4 areunstably fastened, and may be shaken while a user is walking up and downthe staircase.

The simple stepwise insertion and disposition and the support of treadsusing rods may provide a sensation of instability a user.

To remove this sensation of instability, patent document 2 discloses aprefabricated octagonal spiral staircase.

The prefabricated octagonal spiral staircase of patent document 2 is nowdescribed with reference to FIGS. 3 and 4. The prefabricated octagonalspiral staircase includes: a center pillar 16; outside stringer segments10; and treads 20 installed between the center pillar 16 and the outsidestringer segments 10.

-   One side of each of the treads 20 is coupled to the center pillar    16, and the opposite side of each of the treads 20 is coupled to the    side plate 11 of a corresponding one of the outside stringer    segments 10.

However, in patent document 2, the prefabricated octagonal spiralstaircase can be rarely installed unless the prefabricated octagonalspiral staircase is prepared for the dimensions determined through thesufficient understanding of the circumstances of an installation site.

In other words, the center pillar 16 is composed of eight segments 17,18 and 19, and notches to which corresponding treads 20 are coupled andthe number of which is equal to the number of corresponding treads 20are formed in each of the segments.

Accordingly, story heights at all installation sites cannot beaccommodated by the center pillar 16 in which the notches have beenformed in advance, and thus assembly parts suitable for eachinstallation site must be fabricated.

As described above, the staircases of patent documents 1 and 2 cannot beprefabricated for all installation sites and thus have poor versatility,with the result that the assembly and installation properties thereofare considerably degraded.

PRIOR ART DOCUMENTS Patent Documents

(Patent document 1) Korean Patent Application Publication No.10-2004-0101161

(Patent document 2) U.S. Pat. No. 5,737,884

DISCLOSURE Technical Problem

The present invention has been conceived to overcome the above-describedproblems, and an object of the present invention is to provide aprefabricated spiral staircase which can improve versatility so that theprefabricated spiral staircase can be applied to any installation siteeven when story height varies, thereby considerably improving theassembly and installation properties thereof.

Technical Solution

In order to accomplish the above object, a prefabricated spiralstaircase set forth in claim 1 of the present application includes: abase configured to be fastened to a floor; a center pole configured suchthat the lower end thereof is installed on the base; a plurality ofspacers configured to be inserted over the center pole; treads eachconfigured such that one side thereof is inserted over the center polebetween corresponding adjacent two of the spacers; outside stringerseach disposed on the opposite side of the tread; and coupling memberseach configured to couple the opposite side of the tread to the outsidestringer; wherein each of the spacers includes a cylindrical pipe, and alower or upper cap configured to be inserted over the lower or upperside of the cylindrical pipe.

In the prefabricated spiral staircase set forth in claim 2 of thepresent application, one or more height adjustment disks are furtherdisposed internally between the lower cap and the lower end of thecylindrical pipe or between the upper cap and the upper end of thecylindrical pipe.

In the prefabricated spiral staircase set forth in claim 3 of thepresent application, the center pole is a male threaded pole, and nutsare each engaged with the center pole so that the lower cap appliespressure to the one side of the tread.

In the prefabricated spiral staircase set forth in claim 4 of thepresent application, the outside stringers are configured such that atleast a plurality of linear side plates is assembly together and form arectangular shape when viewed in a plan view.

In the prefabricated spiral staircase set forth in claim 5 of thepresent application, each of the coupling members includes: a bracketconfigured to be disposed in a recession formed by cutting out a portionof the opposite side of the tread; first fastening metal elementsconfigured to insert and fasten the bracket into the opposite side ofthe tread; and second fastening metal elements configured to insert andfasten the bracket into the inner surface of a corresponding one of thelinear side plates.

In the prefabricated spiral staircase set forth in claim 6 of thepresent application, each of the brackets includes: a bracket bodyconfigured to have an outer surface adapted to come into contact withthe inner surface of the linear side plate and an inner surface adaptedto come into contact with a side surface of the tread; first throughholes configured to penetrate through the inner and outer surfaces ofthe bracket body, and to be supported by the first fastening metalelements; and second through holes configured to penetrate through thetop surface of the bracket body and the outer surface of the bracketbody or through the bottom surface of the bracket body and the outersurface of the bracket body, and to be supported by the second fasteningmetal elements.

A spacer coupling structure for a prefabricated spiral staircase setforth in claim 7 of the present application includes a center poleconfigured to be fastened to a floor; a plurality of spacers configuredto be inserted over the center pole; and treads each configured suchthat one side thereof is inserted over the center pole betweencorresponding adjacent two of the spacers; wherein each of the spacerscomprises a cylindrical pipe, and a lower or upper cap configured to beinserted over the lower or upper side of the cylindrical pipe.

Advantageous Effects

According to the present invention, the following effects are achieved.

The height of each of the spacers can be adjusted by selectivelyinserting and removing a corresponding upper or lower cap over and fromthe cylindrical pipe, and thus assembly and installation can be easilyperformed even when story height varies depending on an installationsite.

One or more disks are disposed internally between the upper cap and thecylindrical pipe or between the lower cap and the cylindrical pipe, andthus the range of differences in story height can be more rapidly dealtwith. Furthermore, the disks are disposed in the inside, and thus a neatappearance can be provided, thereby enabling the present invention to beconsiderably useful for indoor application.

The nuts are engaged with the male threaded center pole, and thus thelower cap applies pressure to one side of a corresponding tread, therebyfirmly supporting the tread and enabling the staircase to be stablyused.

The outside stringers are configured such that at least a plurality oflinear side plates are coupled to one another and form rectangularoutside stringers when viewed in a plan view, and thus the rectangularoutside stringers have more desirable spatial efficiency than arc-shapedoutside stringers. In other words, in the case where three surfaces arewalls, the corners of the rectangular outside stringers form a rightangle, and thus a wasted space can be removed, thereby providingsignificantly desirable spatial efficiency.

Each of brackets is disposed in a corresponding recession formed througha side surface of a corresponding one of the treads, is fastened to thecorresponding tread, and then is fastened to a corresponding side plate.Accordingly, a separate recession or the like does not need to be formedin the side plate, thereby being considerably useful for the fabricationof a prefabricated staircase. Furthermore, a stable staircase can beconstructed due to high torsional resistance.

In particular, the fastening of the brackets to the side plates isperformed in inclined directions, and thus the support of the treads forthe side plates becomes more firm.

DESCRIPTION OF DRAWINGS

FIG. 1 is a perspective view showing a conventional prefabricated spiralstaircase;

FIG. 2 is an exploded perspective view showing the essential part ofFIG. 1;

FIG. 3 is a perspective view showing another conventional prefabricatedspiral staircase;

FIG. 4 is a schematic plan view of FIG. 3;

FIG. 5 is a perspective view showing a prefabricated spiral staircaseaccording to a preferred embodiment of the present invention;

FIG. 6 is a plan view of FIG. 5;

FIGS. 7 to 11 are perspective views showing the installation of a centerpole on a base;

FIGS. 12 to 14 are perspective views showing the installation of thelowermost spacer;

FIG. 15 a sectional view taken along line 15-15 of FIG. 14;

FIGS. 16 to 20 are perspective views showing the steps of the assemblyof treads and a first outside stringer segment.

FIG. 21 is a sectional view showing the coupling of a spacer accordingto a preferred embodiment of the present invention;

FIG. 22 is a sectional view showing the coupling of a tread and a sideplate according to a preferred embodiment of the present invention;

FIGS. 23 and 24 are perspective views showing a bracket according to apreferred embodiment of the present invention when viewed from anoutside and an inside; and

FIG. 25 is a perspective view showing the installation state of astaircase after poles have been connected to each other.

MODE FOR INVENTION

Preferred embodiments of the present invention will be described withreference to the accompanying drawings below.

Referring to FIGS. 5 and 25, a prefabricated spiral staircase 100according to a preferred embodiment of the present invention includes: abase 200 configured to be fastened to a floor FL; a center pole 300configured such that the lower side thereof is installed on the base200; a plurality of spacers 400 configured to be inserted over thecenter pole 300; treads 500 each configured such that the inner sidethereof is inserted over a portion of the center pole 300 betweencorresponding adjacent two of the spacers 400; outside stringers 600 ato 600 d configured to be disposed on the outer sides of the treads 500;and coupling members 900 configured to couple the outer sides of thetreads 500 to the outside stringers 600 a to 600 d.

As shown in FIG. 8, the base 200 includes a first base 210 configured tobe fastened to the floor FL, and a second base 260 configured to becoupled to the first base 210 and support the lower portion of thecenter pole 300.

As shown in FIG. 7, the first base 210 is formed in a disk shape, and aninsertion hole 211 configured to receive the lower end side of thecenter pole 300 is formed at the center of the first base 210.

Furthermore, first through holes 213 are formed along the edge of thefirst base 210.

First fasteners 215 or the like are inserted into and caught in thefloor FL through the first through holes 213, thereby pressing andfastening the first base 210 into the floor FL.

Furthermore, a plurality of first female threaded holes 217 is formedaround the insertion hole 211 of the first base 210.

The second base 260 configured to hold the lower side of the center pole300 is engaged with and fastened to the plurality of first femalethreaded holes 217.

As shown in FIG. 8, the second base 260 is formed in a cylindricalshape, and a second female threaded hole 261 configured to be engagedwith the center pole 300 is formed at the center of the second base 260.

The second female threaded hole 261 is disposed at a locationcorresponding to that of the insertion hole 211.

A plurality of second through holes 265 configured such that bolts,i.e., second fasteners 263 configured to be engaged with the pluralityof first female threaded holes 217, are disposed therein is formed inthe second base 260.

The second fasteners 263 are engaged with and caught in the first femalethreaded holes 217 though the second through holes 265, as through thefirst through holes 213, thereby pressing and fastening the second base260 into the first base 210.

The center pole 300 is a male threaded pole. As shown in FIG. 15, thecenter pole 300 is engaged with the second female threaded hole 261 ofthe second base 260. The lower end 301 of the center pole 300 is moveddownward through the insertion hole 211 of the first base 210 until thelower end 301 comes into contact with and is stopped by the floor FL.

When the center pole 300 has been engaged with the second femalethreaded hole 261, it is preferred that a loosening prevention nut 310,such as that of FIG. 10, is engaged with the center pole 300 and pushesthe top surface of the second base 260 so as to prevent the second base260 from being loosened due to bolt loosening or the like.

In particular, it is preferred that the loosening prevention nut 310 isimplemented using a washer-based nut.

The height of the center pole 300 may be adjusted based on the height ofa corresponding story by connecting such center poles 300.

In other words, as shown in FIG. 25, the center poles 300, i.e., malethreaded poles, may be coupled to each other via a nut 330 similar to aturnbuckle.

Each of the spacers 400 includes a cylindrical pipe 410, a lower cap 430configured to be inserted over the lower side of the cylindrical pipe410, and an upper cap 450 configured to be inserted over the upper sideof the cylindrical pipe 410.

The cylindrical pipe 410 is formed in a cylindrical shape. It ispreferred that the height of the cylindrical pipe 410 is slightlysmaller than the ordinary height between the treads 500. The reason forthis is that the height of the cylindrical pipe 410 is considerablyuseful to selectively increase and decrease the height between thetreads 500 at an installation site.

Each of the lower and upper caps 430 and 450 includes a horizontalplates 431 or 451 configured to cover the lower surface of thecylindrical pipe 410, and a vertical wall 433 or 453 configured toprotrude from the edge of the horizontal plate 431 or 451 so as to beinserted over the outer surface of the cylindrical pipe 410. It will beapparent that through holes 435 and 455 configured to be inserted overthe center pole 300 are formed at the centers of the horizontal plates431 and 451, respectively.

Accordingly, the height is increased by the thickness of the horizontalplate 431 of the lower cap 430 when the lower cap 430 is inserted overthe cylindrical pipe 410, and is increased by twice the above thicknesswhen the lower and upper caps 430 and 450 are inserted over thecylindrical pipe 410.

In particular, it is preferred that height adjustment disks 440 and 460are further disposed in the corresponding spacer 400.

In other words, when the height adjustment disks 440 and 460 areinserted into an inside between the lower cap 430 and the lower end 411of the cylindrical pipe 410 or into an inside between the upper cap 450and the upper end 413 of the cylindrical pipe 410, the intervals betweenthe treads 500 can be finely adjusted.

It is preferred that a plurality of thin ring-shaped disks is preparedas the disks 440 and 460 and a required number of thin ring-shaped disksare used.

In the present embodiment, each of the lower disk 440 and the upper disk460 is implemented using two disks 441 and 443 or 461 and 463.

As described above, in the present embodiment, the height of the spacer400 can be variously and finely adjusted through the insertion orremoval of the disks 440 and 460 as well as the upper and lower caps 450and 430, and thus the treads 500 can be easily assembled and installedat predetermined intervals even when the height of a story variesdepending on each installation site.

Accordingly, once the spacers 400 according to the present embodimenthave been prepared, installation can be rapidly and accurately performedat any installation site without an effort to produce or machine aseparate part so as to adjust the height.

In this case, since the lower cap 430 a of the lowest one 400 a of theplurality of spacers 400 needs to be inserted over the outercircumferential surface of the second base 260, as shown in FIGS. 11 and15, a through hole 435 a larger than the through holes 435 of thespacers 400 above the lowest spacer 400 a is formed.

The reference symbols of the respective parts of the lowest or startingspacer 400 a are merely made distinct by adding the lowercase character“a” to the corresponding reference symbols of the other spacers 400, andthe functions of the corresponding parts are identical.

Furthermore, as shown in FIG. 21, it is preferred that the disks 440 and460 are coupled and supported inside the upper and lower caps 450 and430 via screws 445 and 465.

As shown in FIGS. 12 and 15, it is preferred that accommodation holes447 and 467 configured to accommodate portions of the screws 445 and 465are formed in the inner circumferential surfaces of the disks 440 and460, and female threads 446 and 466 are preferably formed in the upperand lower caps 450 and 430 so that the female threads 446 and 466correspond to the accommodation holes 447 and 467.

It is preferred that short or long screws are prepared as the screws 445and 465 depending on the heights of the disks 440 and 460. The reasonfor this is to prevent the screws 445 and 465 from protruding above theupper and lower horizontal plates 431 and 451 when the screws 445 and465 have engaged with the female threads 446 and 466.

As shown in FIG. 17, once the first spacer 400 a has been installed, oneside of a first tread 500 is inserted over the center pole 300 anddisposed on the top surface of an upper cap 450 a, the correspondinglower cap 430 of a second spacer 400 is inserted over the center pole300, and then a pressure nut 700 is engaged with the center pole 300 andapplies pressure to the lower cap 430, as in the case of the firstspacer 400 a. Then the lower cap 430 pushes and stably supports the oneside of the tread 500.

As described above, when the spacers 400 are assembled, a number ofpressure nuts 700 equal to the number of spacers are engaged, and thuseach of the treads 500 is firmly supported without shaking.

Protrusions 437 and 457 are formed at the centers of the top surface ofthe lower cap 430 and the bottom surface of the upper cap 450,respectively.

Of the protrusions 437 and 457, the protrusion 437 used for the lowercap 430 functions as a mounting surface configured such that acorresponding one of the pressure nuts 700 is mounted thereon, and alsofunctions as a reinforcement member configured to prevent damage frombeing caused even when the pressure nut 700 is strongly tightenedbecause the thickness of the protrusion 437 is considerably thicker thanthat of the horizontal plate 431.

For reference, only the through hole 435 a is disposed in the horizontalplate 431 a of the lower cap 430 a of the lowest spacer 400 a.

As shown in FIGS. 16 to 20, each of the treads 500 is a plate formed ina shape similar to a fan shape (because the treads are disposed stepwiseto form a spiral shape), a through hole 510 configured to be insertedover the center pole 300 is formed in one (inner) side of the tread 500,and recessions 510 each formed by cutting out a portion of the tread 500in a left square bracket shape are formed in the opposite (outer) sideof the tread 500.

Furthermore, as shown in FIG. 19, a recession 530 or 550 formed bycutting out a portion of a corresponding tread 500 in an “L” shapefitting a newel 630 a or 650 a may be further formed in the opposite(outer) side of the tread 500 depending on the location of the tread500.

It is preferred that protrusions 439 and 459 configured to be insertedinto the through hole 510 are formed at the centers of the upper andlower caps 450 and 430 so as to prevent the through hole 510 of thetread 500 from shaking when disposed between the upper cap 450 on thelower side thereof and the lower cap 430 on the upper side thereof.

The recessions 510 are composed of recessions in a shape the upper,lower and outer sides of which are open.

Brackets 910 which will be described later are disposed in therecessions 510.

As shown in FIGS. 5 and 6, outside stringers 600 a to 600 d are formedin a rectangular shape when viewed in a plan view, and include: a firstoutside stringer segment 600 a, i.e., a starting point; a second outsidestringer segment 600 b configured to be connected to the first outsidestringer segment 600 a; a third outside stringer segment 600 cconfigured to be connected to the second outside stringer segment 600 b;and a fourth outside stringer segment 600 d, i.e., an ending point,configured to be connected to the third outside stringer segment 600 c.

The first outside stringer segment 600 a includes: a first linear sideplate 610 a; a first linear handrail 620 a; first upper and lower newels630 a and 640 a configured to be coupled to the upper and lower ends ofthe first linear side plate 610 a and the upper and lower ends of thefirst linear handrail 620 a; and first balusters 650 a configured to bedisposed between the top surface of the first linear side plate 610 aand the bottom surface of the first linear handrail 620 a.

The second outside stringer segment 600 b is coupled to the firstoutside stringer segment 600 a at a right angle, and includes: a secondlinear side plate 610 b configured such that the lower end thereof iscoupled to the first upper newel 630 a; a second linear handrail 620 bconfigured such that the lower end thereof is coupled to the first uppernewel 630 a; a second newel 630 b configured to be coupled to the upperends of the second linear side plate 610 b and the second linearhandrail 620 b; and second balusters 650 b configured to be disposedbetween the top surface of the second linear side plate 610 b and thebottom surface of the second linear handrail 620 b.

The third outside stringer segment 600 c is coupled to the secondoutside stringer segment 600 b at a right angle, and includes: a thirdlinear side plate 610 c configured such that the lower end thereof iscoupled to the second upper newel 630 b; a third linear handrail 620 cconfigured such that the lower end thereof is coupled to the secondupper newel 630 b; a third newel 630 c configured to be coupled to theupper ends of the third linear side plate 610 c and the third linearhandrail 620 c; and third balusters 650 c configured to be disposedbetween the top surface of the third linear side plate 610 c and thebottom surface of the third linear handrail 620 c.

The fourth outside stringer segment 600 d, i.e., an ending point, iscoupled to the third outside stringer segment 600 c at a right angle,and includes: a fourth linear side plate 610 d configured such that thelower end thereof is coupled to the third newel 630 c; a fourth linearhandrail 620 d configured such that the lower end thereof is coupled tothe third newel 630 c; a fourth newel 630 d configured to be coupled tothe upper ends of the fourth linear side plate 610 d and the fourthlinear handrail 620 d; and fourth balusters 650 d configured to bedisposed between the top surface of the fourth linear side plate 610 dand the bottom surface of the fourth linear handrail 620 d.

A 4′-th inside stringer segment 600 d′ facing the fourth outsidestringer segment 600 d is installed.

The 4′-th inside stringer segment 600 d′ includes: a 4′-th newel 630 d′configured to correspond to the fourth newel 630 d; a 4″-th newel 630 d″configured to be fastened to the uppermost end of the center pole 300; a4′-th handrail 620 d′ configured to be coupled to the 4′-th newel 630 d′and the 4″-th newel 630 d″; and 4′-th balusters 650 d′ configured to bedisposed between the top surface of the last tread 500 b and the bottomsurface of the 4′-th handrail 620 d′.

It is preferred that at least the first upper newel 630 a, the firstlower newel 640 a, and the second newel 630 b are disposed on the floorand function as pillars.

The fourth newel 630 d and the 4′-th newel 630 d′ are fastened to thewall of the slab of a second floor or the like.

Each of the first to fourth linear side plates 610 a to 610 d and thefirst to fourth linear handrails 620 a to 620 d includes an inclinedlinear plate inclined from the lower end thereof toward the upper endthereof.

Each of the first to fourth linear side plates 610 a to 610 d is formedin a plate shape in which the height thereof is larger than a thicknessbetween an outer surface 1 a thereof and an inner surface 1 b thereof,and each of the first to fourth linear handrails 620 a to 620 d isformed in a plate shape in which the height thereof is smaller than thatof the corresponding one of the first to fourth linear side plates 610 ato 610 d.

Furthermore, it is preferred that machining is performed such that theupper and lower sides thereof are parallel or approximately parallel tothe horizontal direction so as to deal with the height differencesbetween the outside stringer segments 600 a to 600 d.

In other words, as shown in FIG. 20, the first linear side plate 610 aincludes: an inclined linear plate 611 a; and upper and lower horizontalplates 613 a and 615 a disposed on the upper and lower sides of theinclined linear plate 611 a.

In the same manner, the first linear handrail 620 a includes an inclinedlinear plate 621 a and upper and lower horizontal plates 623 a and 625 ain a form identical to that of the first linear side plate 610 a.

Accordingly, each of the opposite second to fourth linear side plates610 b to 610 d includes: an inclined linear plate; and upper and lowerhorizontal plates disposed on the upper and lower sides of the inclinedlinear plate.

Furthermore, each of the second to fourth linear handrails 620 b to 620d includes an inclined linear plate and upper and lower horizontalplates in a form identical to that of each of the second to fourthlinear side plates 610 b to 610 d.

Since the upper and lower horizontal plates are disposed, the heightdifferences between segments in upward and downward directions areprevented during the assembly of the segments, and thus the segmentsseem to be continuously connected to one another in their appearance.

Although it is preferred that the handrails are formed in a bar shaperather than a plate shape, it is preferred that the handrails are formedin a plate shape because there occurs the inconvenience in whichseparate bars need to be connected so as to prevent height differences.

As shown in FIG. 22, each of the coupling members 900 includes: abracket 910 disposed in a corresponding one of the recessions 510 of thetreads 500; first fastening metal elements 930 configured to insert andfasten the bracket 910 into a corresponding one of the treads 500; andsecond fastening metal elements 950 configured to insert and fasten thebracket 910 into an inner surface of a corresponding one of the linearside plates 610.

As shown in FIGS. 23 and 24, the bracket 910 includes: a bracket body911; first through holes 913 configured to penetrate through the outerand inner surfaces 911 a and 911 b of the bracket body 911; and secondthrough holes 915 or 917 configured to penetrate through the top andouter surfaces 911 c and 911 a of the bracket body 911 or through thebottom and outer surfaces 911 d and 911 a of the bracket body 911.

The first through holes 913 are horizontal through holes configured topenetrate through two surfaces, i.e., the inner and outer surfaces 911 band 911 a, which are spaced apart from each other.

The second through holes 915 or 917 are divided into 2a-th through holes915 and 2b-th through holes 917 according to the present embodiment andthen described below.

In other words, the 2a-th through holes 915 are through holes configuredto penetrate through two adjacent surfaces, i.e., the top and outersurfaces 911 c and 911 a, of the bracket body 911.

Furthermore, the 2b-th through holes 917 are through holes configured topenetrate through two adjacent surfaces, i.e., the bottom and outersurfaces 911 d and 911 a, of the bracket body 911.

In the same manner, the second fastening metal elements 950 are dividedinto 2a-th fastening metal elements 950 a and 2b-th fastening metalelements 950 b and then described.

It is preferred that the bracket body 911 is formed in a hexahedronshape having front and rear surfaces 911 e and 911 f, the inner andouter surfaces 911 b and 911 a, and the top and bottom surfaces 911 cand 911 d.

When the bracket body 911 is formed in a hexahedron shape, the 2a-ththrough holes 915 correspond to 2a-th inclined through holes 915 havinga positive slope from a top (i.e., the top surface) to a bottom (i.e.,the outer surface), and the 2b-th through holes 917 correspond to 2b-thinclined through holes 917 having a negative slope from a bottom (i.e.,the bottom surface) to a top (i.e., the outer surface).

The plurality of first through holes 913 (which is three in number inthe present embodiment) is disposed in a direction from a front side toa rear side. The number of first through holes 9130 is determined basedon the specifications of a staircase.

The first fastening metal elements 930, such as nails or screws, areinserted into the first through holes 913 and fastened to a side of thetread 500, and thus the first fastening metal elements 930 function tofasten the bracket body 911 to the tread 500.

The 2a-th inclined through holes 915 are disposed above locationsbetween the first through holes 913, and the 2b-th through holes 917 aredisposed immediately below the first through holes 913.

The 2a-th and 2b-th fastening metal elements 950 a and 950 b, such asnails or screws, are inserted into the 2a-th and 2b-th inclined throughholes 915 and 917 and fastened to the inner surface 1 b of the sideplate 610, and thus the 2a-th and 2b-th fastening metal elements 950 aand 950 b function to fasten the bracket body 911 to the side plate 610.

In particular, the 2a-th and 2b-th fastening metal elements 950 a and950 b are fastened in inclined directions, and thus provide strongerresistance against load or torsion than the 2a-th and 2b-th fasteningmetal elements 950 a and 950 b fastened in horizontal directions,thereby increasingly ensuring safety.

Stop protrusions configured to stop the head portions of nails or screwsare formed inside the first through holes 913 and the 2a-th and 2b-thinclined through holes 915 and 917.

Meanwhile, it is preferred that a flange 960 is further formed aroundthe front, rear, and inner edges of the bottom surface 911 d of thebracket body 911.

The flange 960 supports lower end edges of the recession 510 of thetread 500, thereby sustaining larger load.

In particular, when the flange 960 is disposed in a stepped groove 515formed around the recession 510, the flange 960 is disposed in the sameplane in which the bottom surface of the tread 500 is disposed, therebyproviding a desirable appearance.

Furthermore, it is preferred that a downwardly extended portion 970configured to extend downward is further formed on an outer side of thebottom surface 911 d of the bracket body 911.

Third through holes 981 configured such that third fastening metalelements 980, such as nails, screws, or the like, are coupled throughthe third through holes 981 are further formed in the downwardlyextended portion 970.

Stop protrusions configured to stop the head portions of the thirdfastening metal elements 980 are formed inside the third through holes981.

The downwardly extended portion 970 comes into tight contact with theinner surface 1 b of the side plate 610 and is fastened to the innersurface 1 b of the side plate 610 via the third through holes 981,thereby sustaining considerably large load.

It is preferred that finishing plates (not shown) having a coloridentical to that of the tread 500 are attached to the top and bottomsurfaces 911 c and 911 d of the bracket 910 via adhesive, magnets,screws, or the like.

When the finishing plate are fastened via screws, it is preferred thatfemale threads are formed on the top surface 911 c of the bracket 910and the front and rear surfaces of the flange 960.

As described above, although the present invention has been describedwith reference to the preferred embodiments of the present invention, itwill be apparent to those skilled in the art that the present inventionmay be changed or modified and then practiced in various manners withoutdeparting from the spirit and scope of the present invention set forthin the attached claims.

For example, although the outside stringers have been described asincluding the side plates, the handrails, the newels, and the balustersin a broad sense in the detailed description of the present embodiment,it will be apparent that the outside stringers may include only sideplates and may form a spiral staircase in a narrow sense, which isapplied to the present embodiment without change.

DESCRIPTION OF REFERENCE SYMBOLS

100: prefabricated spiral staircase

210 and 260: first and second bases

300: center pole

400: spacer

410: cylindrical pipe

450 and 430: upper and lower caps

440 and 460: disks

500: treads

600 a to 600 d: outside stringers

610 a to 610: linear side plates

620 a to 620 d: linear handrails

630 a to 630 d: newels

650 a to 650 d: balusters

700: (pressure) nuts

900: coupling members

910: bracket

911: bracket bodies

913: first through holes

915 and 917: second inclined through holes

930: first fastening metal elements

950: second fastening metal elements

960: flanges

970: downwardly extended portions

980: third fastening metal elements

984: third inclined through holes

1. A prefabricated spiral staircase, comprising: a base configured to befastened to a floor; a center pole configured such that a lower endthereof is installed on the base; a plurality of spacers configured tobe inserted over the center pole; treads each configured such that oneside thereof is inserted over the center pole between correspondingadjacent two of the spacers; outside stringers each disposed on anopposite side of the tread; and coupling members each configured tocouple the opposite side of the tread to the outside stringer; whereineach of the spacers comprises a cylindrical pipe, and a lower or uppercap configured to be inserted over a lower or upper side of thecylindrical pipe; and wherein one or more height adjustment disks arefurther disposed internally between the lower cap and a lower end of thecylindrical pipe or between the upper cap and an upper end of thecylindrical pipe.
 2. The prefabricated spiral staircase of claim 1wherein the center pole is a male threaded pole, and nuts are eachengaged with the center pole so that the lower cap applies pressure tothe one side of the tread.
 3. The prefabricated spiral staircase ofclaim 1 wherein the outside stringers are configured such that at leasta plurality of linear side plates is assembled together and form arectangular shape when viewed in a plan view.
 4. The prefabricatedspiral staircase of claim 3 wherein each of the coupling memberscomprises: a bracket configured to be disposed in a recession formed bycutting out a portion of the opposite side of the tread; first fasteningmetal elements configured to insert and fasten the bracket into theopposite side of the tread; and second fastening metal elementsconfigured to insert and fasten the bracket into an inner surface of acorresponding one of the linear side plates.
 5. The prefabricated spiralstaircase of claim 4 wherein each of the brackets comprises: a bracketbody configured to have an outer surface adapted to come into contactwith the inner surface of the linear side plate and an inner surfaceadapted to come into contact with a side surface of the tread; firstthrough holes configured to penetrate through the inner and outersurfaces of the bracket body, and to be supported by the first fasteningmetal elements; and second through holes configured to penetrate througha top surface of the bracket body and the outer surface of the bracketbody or through a bottom surface of the bracket body and the outersurface of the bracket body, and to be supported by the second fasteningmetal elements.
 6. A spacer coupling structure for a prefabricatedspiral staircase, comprising: a center pole configured to be fastened toa floor; a plurality of spacers configured to be inserted over thecenter pole; and treads each configured such that one side thereof isinserted over the center pole between corresponding adjacent two of thespacers; wherein each of the spacers comprises a cylindrical pipe, and alower or upper cap configured to be inserted over a lower or upper sideof the cylindrical pipe; and wherein one or more height adjustment disksare further disposed internally between the lower cap and a lower end ofthe cylindrical pipe or between the upper cap and an upper end of thecylindrical pipe.
 7. The prefabricated spiral staircase of claim 2wherein the outside stringers are configured such that at least aplurality of linear side plates is assembled together and form arectangular shape when viewed in a plan view.
 8. The prefabricatedspiral staircase of claim 7 wherein each of the coupling memberscomprises: a bracket configured to be disposed in a recession formed bycutting out a portion of the opposite side of the tread; first fasteningmetal elements configured to insert and fasten the bracket into theopposite side of the tread; and second fastening metal elementsconfigured to insert and fasten the bracket into an inner surface of acorresponding one of the linear side plates.
 9. The prefabricated spiralstaircase of claim 8 wherein each of the brackets comprises: a bracketbody configured to have an outer surface adapted to come into contactwith the inner surface of the linear side plate and an inner surfaceadapted to come into contact with a side surface of the tread; firstthrough holes configured to penetrate through the inner and outersurfaces of the bracket body, and to be supported by the first fasteningmetal elements; and second through holes configured to penetrate througha top surface of the bracket body and the outer surface of the bracketbody or through a bottom surface of the bracket body and the outersurface of the bracket body, and to be supported by the second fasteningmetal elements.